3.1 The drying shrinkage of mortar as determined by this test method is a measure of the decrease in length of test specimens under controlled drying conditions, after an initial period of moist curing.

3.2 Since test specimens are not completely unrestrained during the initial period of moist curing, measurements of drying shrinkage by this test method are most useful for comparative purposes rather than as absolute values.

3.3 The drying shrinkage of unrestrained laboratory tested mortar samples is different from that experienced in a masonry wall where influences include restraint, masonry unit absorption, ambient temperature and humidity, thickness of joint, length of continuous wall, etc.

1.2 This test method is applicable to Specification C270 Type N, Type S, and Type M mortars under the property or proportion specifications. Due to the tendency to damage lower strength specimens during demolding, it is not applicable to lower strength mortars, such as Type O mortars.

1.3 This test method is intended for research purposes only.

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

1.5This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.